Reaction Steps
A solution of tert-butyl (3R)-3-({4-[(2′-oxospiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-1′(2′H)-yl)methyl]phenyl}-amino)pyrrolidine-1-carboxylate (0.53 g, 0.94 mmol) and trifluoroacetic acid (1 mL) in dichloromethane (5 mL) was stirred at ambient temperature for 70 min. The reaction was made basic with 1 M sodium hydroxide (50 mL) and extracted with dichloromethane (4×30 mL). The combined organic solution was dried over sodium sulfate, filtered and concentrated under reduced pressure. Purification by flash column chromatography with dichloromethane/methanol/ammonium hydroxide (14:1:0.15) afforded 1′-{4-[(3R)-pyrrolidin-3-ylamino]benzyl}spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.34 g, 78%) as an off-white solid: mp 118-121° C. (hexanes); 1H NMR (300 MHz, CDCl3) δ 7.23-7.13 (m, 4H), 7.00 (dd, J=7.5, 7.5 Hz, 1H), 6.86 (d, J=7.8 Hz, 1H), 6.55 (d, J=8.4 Hz, 2H), 6.52 (s, 1H), 6.12 (s, 1H), 5.87 (d, J=1.2 Hz, 1H), 5.85 (d, J=1.2 Hz, 1H), 4.99-4.94 (m, 2H), 4.71-4.66 (m, 2H), 3.94-3.85 (m, 1H), 3.83 (br s, 1H), 3.15-3.04 (m, 2H), 2.97-2.88 (m, 1H), 2.83 (dd, J=11.1, 3.0 Hz, 1H), 2.21-2.09 (m, 1H), 1.98 (br s, 1H), 1.67-1.57 (m, 1H); 13C NMR (75 MHz, CDCl3) δ 177.6, 155.9, 148.8, 147.2, 142.3, 132.3, 128.85, 128.80, 124.3, 123.8, 123.3, 119.6, 113.4, 109.6, 103.1, 101.5, 93.6, 80.5, 58.3, 53.9, 53.6, 45.7, 43.8, 33.6; MS (ES+) m/z 456.2 (M+1).
